1. Technical Field
The present disclosure relates to a circuit device, an oscillator, an electronic apparatus, and a moving object.
2. Related Art
In the related art, an A/D conversion circuit which performs analog-digital conversion (hereinafter, referred to as A/D conversion) for converting an analog signal to digital data is widely known. As types of A/D conversion circuit, there are various types such as a flash type, a successive comparison type, and a ΔΣ type. For example, JP-A-2011-223404 discloses a method of performing successive comparison type A/D conversion.
There are various circuits using temperature detection data which is a result of A/D conversion of a temperature detection signal (analog signal) from a temperature sensor unit. For example, in the related art, a temperature compensated crystal oscillator (TCXO) is known. The TCXO is used as, for example, a reference signal source or the like in portable communication terminals, GPS related apparatuses, wearable apparatuses, on-vehicle apparatuses, and the like. A technique disclosed in JP-A-64-82809 is known as related art for a DTCXO which is a digital type temperature compensated oscillator.
If A/D conversion result data as a result of A/D conversion greatly changes in a short period of time, a problem may occur. For example, in a digital type oscillator such as a DTCXO, if a frequency drift of an oscillation frequency caused by a temperature change exceeds, for example, an allowable frequency drift range, it has been proved that various problems occur in an apparatus using an oscillation signal of the oscillator. In other words, it is necessary to suppress a change in temperature detection data which is A/D conversion result data in order to reduce the frequency drift.
It has been proved that a temperature change in a single A/D conversion period under a natural condition is not great. In other words, in a case where temperature detection data at a predetermined output timing is obtained, a change width of temperature detection data at the next output timing may be restricted to a narrow range to some extent.
However, in the technique of the related art disclosed in JP-A-2011-223404 or JP-A-64-82809, none of the above-described content is taken into consideration, and inefficient A/D conversion is performed as a result of permitting a great change in temperature detection data or not taking into consideration the natural condition.